The present invention relates to a technology using a speaker array.
A speaker device having a speaker array on which a plurality of speaker units are arranged, outputs an audio signal with directivity given thereto. This speaker device generates sound with directivity, directs the focus of the sound in a direction of a wall surface, and causes the sound to reach a listener using the wall surface reflection to give the listener a surround sound sensation (for example, JP-A-2006-25153).
If a surround effect is realized by the technology described in JP-A-2006-25153, the listener senses sounds that reach in a variety of directions such as left, right, rearward, and the like, even though the speaker device exists only in front of the listener. Accordingly, the listener can enjoy movies with realistic sensation. On the other hand, a place in which the surround effect can be obtained is limited to a predetermined range since a wall reflection is used therein, and if the listener moves out of the predetermined range, the surround sensation disappears. In viewing an ordinary television program rather than a movie, the listener may watch television while taking another action. In this case, if the listener moves out of the range in which the surround effect is obtained, the stereo sound sensation may disappear and the listener may experience a sense of incongruity due to the change in the sound quality.
In the case where the television program corresponds to a stereo (2-channel) broadcast, the speaker device may direct the focus of the sound in the direction of the listener without using the wall surface reflection so that left channel (Lch) sound reaches the left ear of the listener and right channel (Rch) sound reaches the right ear of the listener. In this case, however, the listening area of the listener becomes narrow. Accordingly, due to a slight movement of the listener, the stereo sound sensation may not be obtained, and the listener may experience a sense of incongruity due to the change of the sound quality. Also, since Lch sound and Rch sound are output from all the speaker units, the listener may experience a low sense of separation of sound images for the respective channels, and thus no great stereo sound sensation may be obtained.
On the other hand, a speaker device that can give directivity to sound also can output sound so as to be spread out to the front of the speaker device (the listener side as seen from the speaker device). In this case, if a virtual focus that is a virtual output position of the sound (hereinafter referred to as a “virtual focus”) is positioned on the rear side of the speaker device, the sound output range widens toward the listener side (see FIG. 5). On the other hand, as described above, since the Lch sound and the Rch sound are output from all speaker units, the sense of separation of sound images for the respective channels becomes low. Also, the Rch sound is output so as to be spread out mainly to the left side of the listener and the Lch sound is output so as to be spread out entirely to the right side of the listener, and for example, if the listener moves to the left side (the left side as seen from the listener who faces the speaker device as shown in FIG. 5B), in spite of the fact that the listener moved to the left side, the listener may hear the Rch sound louder than the Lch sound, and may experience a sense of incongruity with respect to the left/right volume balance.